Most patients with brachial plexopathies complain of vague ipsilateral and nonspecific symptoms. Trauma is the most common cause of brachial plexopathy; tumors are the next most common cause. Magnetic resonance imaging yields important information regarding etiology and the specific location of pathology, and can aid in directing possible therapy.
is a Clinical Assistant Professor of Radiology and
is a Professor of Radiology and Section Chief of Neurology in the
Department of Radiology, University of North Carolina School of
Medicine, Chapel Hill, NC.
Most patients with brachial plexopathies complain of vague
ipsilateral and nonspecific symptoms. Trauma is the most common
cause of brachial plexopathy; tumors are the next most common
cause. Infection of the brachial plexus (BP) is rare and may occur
after lung disease, such as fungal infection or tuberculosis, or
after surgery or trauma.
Viral brachial plexitis is rare, and postviral inflammatory
processes are also known to affect the BP. Both are self-limiting
processes and usually resolve 6 to 12 weeks after their onset. A
plexopathy may also arise as a consequence of drug allergy. The
heredo-familial form of brachial plexopathy is rare and is seen
mostly in men. Postradiation plexopathy is more often seen in
patients receiving >6000 cGy.
At our institution, magnetic resonance (MR) is the preferred
modality for imaging of the BP.
To image the BP, we use a large field-of-view (to include both
shoulders) and obtain T1-weighted coronal, T1-weighted axial, and
T2-weighted axial images (Figure 1A). Using a small field-of-view,
we obtain parasagittal T1-weighted images of each BP (Figure 1B).
After contrast is given, we repeat the coronal and axial T1weighted
images. Fat suppression is recommended for T1-weighted images after
contrast administration and is helpful when evaluating certain
masses, such as lipomas, in the vicinity of the BP (Figure 2).
Fat-suppressed images are also very helpful to evaluate for trauma
of the BP. In these images, the injured BP is generally of high
On sagittal views of the BP, we generally include the cervical
spine because disc herniations occasionally result in symptoms
mimicking a plexopathy. The cervical rib syndrome may also result
in ipsilateral brachial plexopathy.
It is associated with the presence of an extra rib (cervical rib)
and is more common in women. When suspected, the presence of the
extra rib may be confirmed by the use of radiographs. This syndrome
tends to be unilateral, but bilateral symptoms are occasionally
The components of the BP may be recalled by using the following
(branches). Although classical anatomy uses the above components,
imaging anatomy is greatly simplified (Table 1).
The imaging anatomy scheme uses easily identifiable landmarks
(such as the anterior and middle scalene muscles and subclavian
artery) to divide the BP.
The innervation provided by the brachial plexus is reviewed in
Most traumatic avulsions are seen in newborns (generally due to
shoulder dystocia at vaginal delivery) and in young adults
(particularly after motorcycle accidents).
Erb's palsy, involving avulsion of C5-6, comprises 80% to 90% of
brachial plexopathies in the newborn.
In this palsy, the affected arm is internally rotated and adducted,
the elbow extended, the forearm pronated, and the wrist is flexed.
Complete recovery can occur but may take months. All
supraganglionic avulsions have a poor prognosis. Dejerine-Klumpke
palsy is rare, comprising only 1% of all brachial plexopathies in
In these patients, the elbow is flexed, the forearm is supinated,
the wrist is extended, and there is claw-like deformity of the
hand. The muscles in the involved arm are weak and Horner's
syndrome may be present. Resolution of this plexopathy is possible.
The third type of brachial plexopathy in the newborn (accounting
for approximately 10% of cases) is a complete avulsion of the BP,
resulting in absolute weakness and lack of muscle control and tone.
There is no treatment for this type of injury, and there is no
recovery. In about 10% of all neonatal brachial plexopathies, the
involvement is bilateral. Injury to the BP may also occur if one
arm is kept in an awkward position for prolonged periods of time.
Avulsion of the BP at its spinal cord origin results in
formation of intraspinal or extraspinal cerebrospinal fluid
collections and/or hematomas.
Pseudo-meningoceles will appear in 80% of patients with avulsions,
but not all of these will fill with contrast at myelography.
The sensitivity and specificity of postmyelogram computed
tomography (CT) are 73% to 83% and 87% to 100%, respectively, in
avulsions of BP (because of the lack of filling of the
pseudomeningoceles, which is the most important CTfinding in
Thus, MR is a better imaging method for detecting avulsion of the
BP than is postmyelogram CT. MR myelography is helpful in
(Figure 3). Establishing the site of injury will help decide the
mode of treatment.
For supraganglionic avulsions, there generally is no treatment,
whereas intraganglionic or distal avulsions may undergo
microsurgical re-anastomosis and/or grafting. Some supraganglionic
avulsions may be treated by microsurgical anastomosis. Most of
these patients will not recover any significant function, but the
procedure will decrease their pain. Hematomas in the vicinity of
the BP may require decompression to avoid pressure necrosis of the
nerves, and subclavian artery aneurysms and pseudoaneurysms may
need to be clipped, occluded, or stented (Figure 4). Chronic
injuries manifest as atrophy and gliosis of the spinal cord at the
level of the avulsion.
Sensory symptoms are seen mostly in adults and may occur after
radiation or indicate the presence of a tumor.
In postirradiation plexopathy, the nerves are enlarged diffusely
and typically appear as high signal on T2-weighted sequences
(Figure 5). The BP may also show some enhancement after gadolinium
Tumors commonly produce both motor and sensory symptoms. Patients
with both a BP palsy and Brown-Séquard's syndrome usually have an
injury at the level of the root entry zone into the cord.
Involvement of the phrenic nerve and scapular winging indicate an
injury to the supraclavicular BP. A BP palsy with Horner's syndrome
indicates an injury to the infraclavicular segment.
Primary tumors occur in younger patients and may be
nerve-related (schwannoma/neurofibroma) or sarcomas
(Figure 6). Benign tumors are generally well-demarcated and enhance
variably. Sarcomas may be either well-demarcated or infiltrative.
Secondary tumors are generally seen in older patients and include
lung cancer (Pancoast's tumor) and metastases (commonly from
primary breast cancer) (Figures 7 and 8). In patients with early
Pancoast's tumor, the only clue to the presence of a lesion may be
a lesion of intermediate signal intensity effacing the normal
bright T1 appearance of the triangular region of fat located
superior to the lung apex, medial to the scalene muscles and
lateral to the spine. Larger tumors are easier to identify. In all
of these tumors, multiplanar imaging is necessary to exclude
invasion of the BP, which may preclude surgery.
Occasionally, lymphoma and leu-kemia (including chloromas) may
also involve the BP. These tumors are generally ill-defined and
infiltrative and enhance after gadolinium is administered. Benign
masses may result in symptoms by virtue of compression of the BP,
whereas malignant ones compress, infiltrate, and destroy it.
Imaging also plays a role in treating chronic pain associated
with BP pathology. This may be treated by ablation of the plexus,
which is generally done by injecting alcohol into the proximal
aspect (trunks) of the plexus. The trunks are localized by CT in
between the anterior and mid/posterior scalene muscles. The lysing
material is combined with iodinated contrast so that its
distribution can be tracked with CT.
Brachial plexopathy is most commonly the result of trauma or
tumor. Imaging with MR yields important information regarding
etiology and the specific location of pathology, and can aid in
directing possible therapy.